The invention concerns a valve, particularly a solenoid valve, with an inlet connection and an outlet connection, having between them a shut-off device with a valve seat and a closure member.
In the following, the invention is described on the basis of a valve, which is meant for a humidification system. Such a valve controls relatively small amounts of fluid, for example, one to five liters per minute.
The invention is based on the task of providing a valve for small output quantities, with a simple design.
In a valve as mentioned in the introduction, this task is solved in that the closure member has a closing element and a tappet separate from the closing element, the closing element being held in a guiding arrangement.
Thus, it is possible to select practically any desired element as closing element, that is, also a relatively small component, which is able to close a correspondingly small valve seat. Since it is no longer required to fix the closing element on the tappet, the material for the closing element can be selected relatively freely. A material may be chosen that is particularly well suited for the fluid to be dosed. As the closing element is separated from the tappet, the guiding arrangement is provided to ensure that the closing element always returns to its bearing on the valve seat.
In a preferred embodiment, it is provided that in an open position the closing element bears on an auxiliary valve seat, which is connected with a tank connection, the guiding arrangement being arranged between the valve seat and the auxiliary valve seat. When the valve is open, the passage between the outlet connection and the tank connection is blocked. The fluid to be controlled thus gets direct from the inlet connection to the outlet connection. When, however, the valve is closed, the outlet connection is connected with the tank connection, as the closing element has released the auxiliary valve seat. Thus, a dropping at the outlet of the valve is prevented, when the valve is closed. In this connection, the guiding arrangement is exactly in the right position, that is, it guides the closing element from the valve seat to the auxiliary valve seat and back. Additionally, it constitutes a flow resistance, which prevents a short-circuiting between the valve seat and the auxiliary valve seat, while the closing element is moving.
Preferably, the guiding arrangement has an opening, in which the closing element is arranged, the diameter of the opening being equal to a diameter defined by the closing element plus a predetermined amount of play. Thus, it is ensured that the closing element can move without, or at least with only little, friction in the guiding arrangement. In addition, the opening in the guiding arrangement is substantially closed during movement of the closing element, during which the closing element bears on neither the valve seat nor the auxiliary valve seat, so that no unimpeded flow can take place from the valve seat to the auxiliary valve seat.
Preferably, the guiding arrangement includes a guide element in the shape of a bowl, which opens in the direction of the valve seat. The guide element ensures that the fluid cannot either create a short-circuiting path between the valve seat and the auxiliary valve seat by simply flowing around the closing element and the guiding arrangement. On the contrary, the path between the valve seat and the auxiliary valve seat is extended because of the guide element. The fluid is redirected by the bowl-shaped embodiment, so that a substantial throttling resistance is generated during the opening or closing movement of the closing element. This throttling resistance is sufficient to prevent significant fluid losses. In this connection, it must be observed that the time in which the risk of short-circuiting exists, is relatively short.
Preferably, the valve seat is arranged at the top of a pipe element that extends in the direction of the guide element. Thus, the fluid leaving the valve seat is initially redirected, before it can continue its flow. In the open state of the valve, this redirecting causes no problems, as the flow passage is small and throttling resistances play no significant part. For the opening process, however, the throttling resistance is sufficiently increased.
It is particularly preferred that the guide element and the pipe element create a gap, which is uniformly wide in the radial direction. Thus, the fluid is specifically guided, without being whirled. At increasing radial distance from the valve seat, the gap provides an ever increasing flow cross section, so that the fluid can propagate.
Preferably, an expanding zone is fitted to the gap, which zone opens radially in relation to the valve seat. Such an embodiment reduces the flow resistance in the open state, however, during the opening movement permits only a small fluid quantity to migrate from the valve seat to the auxiliary valve seat.
Preferably, the guide element has, in the area of the expanding zone, a radially extending circumferential flange. This circumferential flange can be used for the safe fixing of the guiding arrangement in the valve housing. The circumferential flange provides surfaces, which are perpendicular to the force, with which the fluid flowing through the valve seat acts upon the guiding arrangement.
Preferably, the guiding arrangement is made of a plastic material, however, the present invention is not limited in this regard. Plastic materials are easily shaped and adapted to predetermined functions. Additionally, they are able to work together with the closing element at low friction, which is particularly advantageous, when the valve is used for controlling the water in a humidification system.
Preferably, the guiding arrangement is fixed in a housing by means of a retaining part. The retaining part can be adapted to the housing and the guiding arrangement can be adapted to the retaining part. This simplifies the design of the housing and the mounting.
Preferably, the valve has a nominal output in the range from 1 to 5 l/min. Such small outputs are preferably required in irrigation structures.
It is also preferred that the closing element is made as a ball with a diameter in the range from 1 to 4 mm however the invention is not limited in this regard. A ball has the advantage that it needs no definite orientation in the valve to bear sealingly on the valve seat and on the auxiliary valve seat. Due to the small size, it is not possible to fix the ball on the tappet. In the embodiment shown, however, this is not necessary.